Checking Monitor Status

NOTE: The monitor status (mode 6) is not applicable to the heated oxygen sensor (HO2S). However, HO2S test values can be checked by O2S TEST RESULT (mode 5). (See CHECKING MONITOR STATUS )

Outline
The monitor results and the test values can be checked with the OBDII scan tool.

The engine control module (ECM) monitors the emissions-related components as the thermostat, catalyst converter and evaporative emissions (EVAP), and determines whether they are functioning normally or not. When finished monitoring, the ECM stores the monitor results and the test values.

The monitor result indicates whether the component is functioning normally or not. The test value is the value that was used to determine the monitor result. If the test value is outside the test limit (malfunction criterion), the ECM determines the component is malfunctioning. Some emissions-related components have multiple test values to determine monitor result. If one of these test values is outside test limit, the ECM determines the component is malfunctioning.

Description

The test value and test limit information are described as shown in the following table. This information is included under "MONITOR RESULT" in the emissions-related DTC information:

TID $08: Thermostat

TID $08: THERMOSTAT CHART

TLT	CID	Unit Conversion	Description of Test Value	Description of Test Limit
1	$01	Multiply by 0.625 and subtract 40 (°C)	ECT sensor output when estimated ECT has reached to malfunction criterion	Malfunction criterion for thermostat

TID (Test Identification Data) is assigned to each emissions-related component.
TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.

If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
CID (Component Identification Data) is assigned to each test value.
Unit Conversion is used to calculate the test value indicated on generic OBDII scan tools.

Procedure (using intelligent tester)
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch and intelligent tester ON.
3. Clear DTCs.
4. Allow the vehicle to drive, in accordance with the applicable drive pattern described in READINESS MONITOR DRIVE PATTERN .
5. Select the intelligent tester menus: DIAGNOSIS, ENHANCED OBDII, MONITOR INFO and MONITOR RESULT. The monitor result appears after the component name.
  - INCMP indicates the component has not been monitored yet.
  - PASS indicates the component is functioning normally.
  - FAIL indicates the component is malfunctioning.
  Fig 1: OBD II Scan Tool Display - Monitor Result
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
6. Select the component and press ENTER. If the monitor result has been PASS or FAIL, the accuracy test value appears.
  - VAL indicates the test value.
  - LMT indicates the test limit (malfunction criterion).
  - TLT indicates the test limit type.
7. Compare the test value with the test limit.
  - If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
  - If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
  - If the test value is on the borderline of the test limit, a malfunction is concealed in the component.

HINT:

The monitor result might on rare occasions be PASS even if the malfunction indicator lamp (MIL) is illuminated. This indicates the system malfunctioned on a previous driving cycle. This might be caused by an intermittent problem.

Fig 2: OBD II Scan Tool Display - Thermostat Malfunction